I have a small Gas Webber (JL Sell them), eliptical shape, brilliant and so very easy to clean. I've had numerous Gas BBQ's over the years and because of all the fiddly bits I find I get rid of them as they just dont stay clean enough. The griddle is best if enamel coated, avoid Stainless Steel like the plague, Cast Iron is ok (my present one is CI) as they clean up fine but enamel coated is miles better. Look for nooks and crannies that support stuff, because a GAs BBQ doesnt get as hot as a charcoal one and charcoal ones tend not to have fancy supports the gas ones just gum up with fat eventually. Except my Webber, it comes off the stand and can be taken indoors for a good scrub up, very few crevices and the burner doesnt mind getting wet.
HTH
Matt